Diffusion-weighting caused by spoiler gradients in the fast imaging with steady-state precession sequence may lead to inaccurate T 2 measurements in MR fingerprinting

Abstract

Magnetic resonance fingerprinting (MRF) is a promising framework that allows the quantification of multiple magnetic resonance parameters with a single scan. MRF using fast imaging with steady-state precession (MRF-FISP) has robustness to off-resonance artifacts and has many applications in inhomogeneous fields. However, the spoiler gradient used in MRF-FISP is sensitive to diffusion motion, and may lead to quantification errors when the spoiler moment increases. In this study, we examined the effect of the diffusion weighting in MRF-FISP caused by spoiler gradients. The T 2 relaxation times were greatly underestimated when large spoiler moments were used. The T 2 underestimation was prominent for tissues with large values of T 2 and diffusion coefficients. The T 2 bias was almost independent of the apparent diffusion coefficient (ADC) and T 2 values when the ADC map was measured and incorporated into the matching process. These results reveal that the T 2 underestimation resulted from the diffusion weighting caused by the spoiler gradients.